1. Field of the Invention
This invention relates to a water-soluble, foam-inhibiting universal lubricant based on an aqueous self-emulsifying solution consisting of a mixture of an ethoxylated dimeric fatty acid and a foam inhibitor.
It has been known for some time that, on account of their limited cooling properties, water-insoluble or water-immiscible oils, such as mineral oils or unsaturated fats, are not necessarily lubricants of choice, particularly in the metalworking field. Due above all to the distinct increase in processing speeds and abrasion levels, greater importance is being attributed to the dissipation of heat and, hence, ultimately to the water-miscible or water-soluble universal lubricant. This technological change on the part of the metalworking industry on the one hand and the major change in the approach to works safety and pollution control on the other hand have resulted in a reduction in the mineral oil component through the use of so-called synthetic universal lubricants based on water-soluble constituents free from mineral oils. Taking on-going developments in the surfactants field into consideration, nonionic surfactants in particular have contributed to a major advance in water-miscible or water-soluble lubricants. In this way, water-miscible lubricants, but especially emulsifying or water-soluble lubricants based on a w/o emulsion or a genuine soap solution, have been successfully used to an increasing extent (cf. J. Muller, Tribologie und Schmierungstechnik, Vol. 35, pages 128-132, 1988).
Discussion of Related Art
DE-OS 36 09 039 and DE-OS 36 11 027 describe cold-rolling oils having a low dimeric fatty acid or polymeric fatty acid content of less than 10% by weight, the dimeric fatty acids preferably being derived from monomeric fatty acids containing 16 to 20 carbon atoms of the oleic acid, linoleic acid, gadoleic or zoomaric acid type. However, where these dimeric fatty acids are used in relatively large quantities by weight, unwanted "oil residues" are said to occur "to a remarkable extent".
PCT/WO 88/05809 reports on the use of ethoxylated or propoxylated Guerbet alcohols and esters thereof as lubricants in the processing of, in particular, aluminium cans from the beverage industry. For example, dimeric fatty acid mixtures consisting of dimerized oleic acid, linoleic acid, elaidic acid and tall oil fatty acid components are also used for the esterification.
Now, the problem addressed by the present invention was to provide a totally new concept for a water-soluble universal lubricant which would consist of a mixture of a synthetic oil based on dimeric fatty acid and a certain foam inhibitor.